PROJECT SUMMARY Both the clearance of hepatitis C virus (HCV) and its disease manifestations are associated with the inflammatory response. Yet, large gaps in knowledge exist about the factors that initiate inflammation and control HCV replication. There is an urgent need to fill these gaps because determining the mechanisms that control HCV infection and associated inflammation is imperative for understanding HCV-associated disease. The long-term goal of this collaborative team is to understand the mechanisms of HCV innate control and pathogenesis. Consistent with this goal, the overall objective in this proposal is to determine how the RNA triphosphatase DUSP11 is associated with control of both HCV infection and pro-inflammatory RNA transcripts. The central hypothesis is that DUSP11 promotes turnover of pro-inflammatory host and viral triphosphorylated transcripts, thereby reducing HCV replication and RNA-associated inflammation. The rationale for this proposed research is that, once it is known how DUSP11 functions in control of virus replication and host pro-inflammatory transcripts, this will advance understanding of the innate defenses against HCV, imperative for guiding future rational vaccine designs and for developing therapeutic strategies to address HCV-induced liver pathogenesis. Testing the central hypothesis and completing the objectives outlined in this proposal will be accomplished via the following two specific aims: 1) Determine the anti-HCV mechanism of DUSP11 in liver cells, and 2) Determine the function of DUSP11 in controlling inflammation associated with pro-inflammatory viral and host RNAs. Under the first aim, knockout approaches combined with cell, molecular and biochemical experiments will reveal how DUSP11 and its partners inhibit HCV virus infection and how the virus counters this restriction by binding the cellular microRNA, miR-122. Under the second aim, specialized high-throughput tri-phosphate-specific RNA sequencing technology combined with knockout mice will determine how DUSP11 controls inflammation associated with viral and host pro- inflammatory RNAs in cultured cells and in vivo. The contribution here is expected to be a detailed understanding of the mechanisms of how DUSP11 restricts HCV replication and modulates pro-inflammatory activities of viral and host RNAs during infection. These contributions will be significant because they are expected to have broad translational importance for understanding the activity and possible viral resistance mechanisms of current phase II anti-miR-122 HCV drugs as well as informing the interface of innate and adaptive immune response ? key for rational vaccine design. The research proposed in this application is innovative because it represents a new and substantive departure from the status quo by focusing on DUSP11, a single protein that promotes both restriction of HCV and control of inflammation triggered by host and viral RNAs. The results from this proposed work will have a positive impact because they will expand understanding of HCV disease and likely guide the design of preventative and therapeutic strategies.